1. Field
Embodiments relate to a liquid crystal display (LCD) device and a method of driving the LCD device, and more particularly, to a LCD device with reduced afterimage and a method of driving the LCD device.
2. Description of the Related Art
Liquid crystal display (LCD) devices are widely used as display devices of laptop computers or mobile televisions due to their properties, including lightweight, small thickness, and low-power consumption.
A LCD device is formed by attaching a thin-film transistor TFT substrate, on which a TFT array is formed, and a color filter substrate, on which a color filter array is formed, to each other via a liquid crystal layer. The TFT substrate and the color filter substrate are attached to each other, e.g., with a sealant along borders of the TFT substrate. Alignment films are formed on surfaces of the TFT substrate and the color filter substrate facing each other and are rubbed so that liquid crystals of the liquid crystal layer are aligned in a uniform direction.
A LCD device displays data to be displayed by applying a voltage to liquid crystals by using dielectric anisotropy and refractive index anisotropy of the liquid crystals arranged between a TFT substrate and a color filter substrate. When the same image is displayed for a long time, even if the image is changed to another image, image quality is deteriorated due to an afterimage phenomenon by which the pattern of the previous image remains. An afterimage is formed due to a residual DC voltage formed in the liquid crystal layer.
FIGS. 1A and 1B illustrate schematic diagrams for describing the afterimage phenomenon of a liquid crystal panel. Referring to FIGS. 1A and 1B, when a DC voltage is applied to a liquid crystal layer adjacent to an alignment film, impurities in the liquid crystal layer are ionized. Here, positive ion impurities accumulate on an alignment film with negative polarity, whereas negative ion impurities accumulate on an alignment film with positive polarity. With the lapse of time, the ion impurities are attached to the alignment films, and thus, liquid crystal molecules acquire DC voltages due to the ion impurities attached to the alignment film. The DC voltages of the liquid crystal molecules are referred to as the residual DC voltages. The residual DC voltage changes alignment direction of the liquid crystal molecule by changing the pre-tilt angle, which is an optical parameter of the liquid crystal molecule, and thus, the liquid crystal molecules may become less sensitive when signal voltages applied from outside are changed. Therefore, if the same image is displayed for a long time, the pattern of the image remains due to accumulated charges even if the image is changed to another image.